XS Server Hardware
This is a description of the first dedicated hardware implementation of the School server. An overview of the services provided by the School server is provided by the Server Services document, with an accompanying discussion of desired services. Also available is a description of the first software implementation.
Contents
Introduction
Unlike the current laptop, there will be a number of School server hardware platforms. OLPC, in order to support the deployment of laptops, especially in environmentally hostile or off-the-grid locations, is designing a reference platform in collaboration with our manufacturing partner, Quanta. We are also supporting efforts by candidate countries (such as Brazil) to manufacture a school server platform locally.
Current platforms include:
- XSX - A short-term prototype, available now using OTS parts
- An XO laptop - Equipped with an external disk drive, a laptop should be capable of performing as a school server for small (less than thirty laptop) schools.
- XS - An environmentally rugged, very low power school server for up to 150 students. Should be available in November.
XS Specifications
This is a School server hardware platform designed with low power consumption and operation in environmentally challenging conditions as goals.
Processor
This hardware platform may be based on any processor architecture supported by the mainstream Linux kernel and libc software trees. We encourage the use of processors supported by Fedora Core 7.
Processor performance is difficult to characterize with a single number. We are looking for between 1200 and 1600 MIPs, capable of 120K+ interrupts/sec, with at least 1 GB/sec of memory throughput. At least 256KB of L2 cache should be provided.
For the XS Server, the processor is a PowerPC, the MPC7447A from Freescale, with AltiVec support. Apple calls it a G4.
Network Interfaces
The following are the integrated networking interfaces on XS. Additional interfaces may be added to the system using the peripheral interfaces.
Wireless Mesh
The School server will have two or three Active Antenna, an 802.11b/g WiFi wireless mesh networking interface. Each one of these serves as a mesh portal point operating on one of the three non-overlapping 802.11b channels (1, 6, and 11).
While connected to the school servers using detachable five meter USB cables, the Active Antennas are considered integrated as there must always be at least one of these connected for proper server operation. In the future, higher numbers (four or five) of more advanced (directional) Active Antennas may be used.
These are not integrated physically into the XS school server. This allows them to be located optimally for RF transmission/reception, while the server is in a more accessible location. It also allows for greater separation of the three antennas, operating simultaneously at neighboring frequencies.
Wired Networking
Providing at least two wired ethernet interfaces allows for reliable, high-bandwidth connection between a school server and its internet connection (if through a DSL or satellite modem), other school servers, and any non-laptop computer equipment.
The current plan for XS is to provide two 1000baseT ports and four 100baseT ports on the server. The two high speed ports allow multiple servers in a school to form a high speed backbone, and the four additional ports on each server provide school network expansion without using external switches. External switches are not encouraged, due to unknown quality and the requirement of external power.
Each port will be provided with two LEDs indicating link status, simplifying network debugging.
Peripheral Interfaces
The following peripheral interfaces are provided for expanding the capabilities of the school server.
USB 2.0
At least six Universal Serial Bus (USB) 2.0 interfaces should be provided for extending the storage and communication capabilities of a School server.
This assumes that up to three external ports will be used for Active Antenna, another for an external CD/DVD RW, another for a possible WAN connection, and one last one for temporary USB key or external USB drive attachment.
The total amount of power consumed by the USB devices will be clamped to 2.5 A at 5 Volts (12.5 W) total, aggregrated across all devices. Any single device may pull up to 1.5 A (7.5 W).
PCI-Express Slot
A short, full height PCI-Express (4 channel) expansion slot is provided internally in the XS. This slot is intended for the addition of a DVB-S receiver and demodulator, but may be used for other purposes as well.
The power consumption of this expansion slot limited to 15 W. Exceeding this will lower the maximum ambient operating temperature of the server, and may also prevent the use of a second disk drive.
Non-Volatile Storage
Internal Disk Drive
One internal 3.5 in. disk drive will be provided. The disk interface will be SATA (version 1 or 2). The capacity of this disk drive WILL vary, with a minimum size of 300 GB at this time.
A second 3.5 in. disk drive will be supported in the XS, primarily for onsite drive replacement, but also allowing storage expansion. Use of a second disk drive will significantly increase the power consumption of the server.
A fan-less aluminum disk drive cooler may be worthwhile as a prevention of overheating measure.
Network Attached storage off-site may be a good choice concerning prevention of theft and natural disaster destruction, war conflict, etc.
My Book™ World Edition™
WDG1NC10000
Network Storage System with Remote Access 1 TB, Ethernet
Anywhere, Anytime Access Share Photos and Documents Data OnHand™
Access your data anywhere, anytime, even when your local computer is off.
Some specific options and Manufacturers with their features & proprietary technologies: Shock resistance; error correction; prevention; electricity energy efficiency; encryption & security; etc.
Western Digital:
http://www.westerndigital.com/en/products/productcatalog.asp?language=en
GreenPower™ Hard Drives GP drives from WD yield average drive power savings of 4-5 watts over competitors' drives while maintaining solid performance.
http://www.westerndigital.com/en/products/greenpower/index.asp
http://www.westerndigital.com/en/products/greenpower/family.asp?language=en
WD RE2-GP WD5000ABPS SATA Hard Drives 500 GB, 16 MB Cache, Power-saving
RAID-specific time-limited error recovery (TLER) - Pioneered by WD, this feature prevents drive fallout caused by the extended hard drive error-recovery processes common to desktop drives.
http://www.westerndigital.com/en/products/products.asp?driveid=386&language=en
WD Caviar® GP WD5000AACS
SATA Hard Drives 500 GB, SATA 3 Gb/s
Key Features Reduced power consumption - WD has reduced power consumption by up to 40 percent compared to competitors’ drives with the combination of WD's IntelliSeek™, IntelliPark™, and IntelliPower™ technologies.
Helps enable eco-friendly PCs - WD Caviar GP drives yield average drive power savings of 4-5 watts over competitors’ drives making it possible for our energy-conscious customers to build systems with higher capacities and the right balance of system performance, ensured reliability, and energy conservation. This power savings equates to reducing CO2 emission by up to 13.8 kilograms per drive per year - the equivalent of taking a car off the road for 3 days each year*. By using environmentally-conscious PCs with our WD Caviar GP drives on board, large organizations with many desktop computers can minimize their carbon footprint and save real money on electricity costs.
- Assumes that a car produces 1.60 CO2 pounds per Kwatt/hours/year. Calculation of automobile emissions depends on the car's g/km emission levels and km/year of driving.
Cool and Quiet - GreenPower technology yields lower operating temperatures for increased reliability and low acoustics for ultra-quiet PCs and external drives.
Perfect for external drives - External drive manufacturers can eliminate the need for a fan in a high-capacity product with a WD Caviar GP drive, the coolest and quietest in its class. External drives with WD Caviar GP drives on board can save up to $14.00 per year in electricity costs. See our power savings chart for details.
IntelliPower - A fine-tuned balance of spin speed, transfer rate and caching algorithms designed to deliver both significant power savings and solid performance. Additionally, GreenPower drives consume less current during startup allowing lower peak loads on systems as they are booted.
IntelliSeek - Calculates optimum seek speeds to lower power consumption, noise and vibration. View demo >
IntelliPark - Delivers lower power consumption by automatically unloading the heads during idle to reduce aerodynamic drag.
Perpendicular Magnetic Recording (PMR) - Employs PMR technology to achieve even greater areal density.
StableTrac™ - The motor shaft is secured at both ends to reduce system-induced vibration and stabilize platters for accurate tracking, during read and write operations. (750 GB and 1 TB only)
Seagate may be a proper choice for a vendor for the internal disk drive.
Barracuda ES.2 SATA 3.0-Gb/s 500-GB Hard Drive
ST3500320NS
The Barracuda® ES2 drive is perfect for high-capacity, 7200-RPM nearline storage where dollars/GB and watts/GB are primary metrics. It offers energy-saving PowerTrim™ features, internal data integrity protection, superior rotational vibration tolerance and a SATA 3.0-Gb/s interface.
Key Features and Benefits
* Perpendicular recording technology for maximum capacity * 24x7 operation and 1.2 M hrs. MTBF * Dynamic power saving using Seagate PowerTrim™ technology * Broad spectrum rotational vibration tolerance at 12.5 rads/s2 * Error recovery control - quick error resolution to prevent system timeouts * Workload management to ensure operational reliability * Quick and robust download with firmware security checks * Write Same command for efficient RAID initialization * Idle Read After Write data integrity checking * 32-MB cache * Low total cost of ownership * 5-year limited warranty
Momentus® Hard Drives
http://www.seagate.com/www/en-us/products/laptops/momentus/
Seagate® Momentus® hard drives provide the optimum combination of performance, capacity and mobility in a 2.5-inch form factor. They are also a good fit in certain non-PC applications, including external storage, copiers/printers and entry-level blade servers.
Seagate delivers desktop-like performance with the Momentus 2.5-inch laptop hard drive. Seagate Momentus drives offer high-capacity storage while conserving battery life. Perpendicular recording technology provides increased hard-drive storage capacity—up to 160 GB on a 2.5-inch drive. Momentus drives solve the needs of small- to medium-size businesses with features such as full disk encryption with no performance degradation and hybrid technology to enhance the value of Microsoft Windows Vista. Seagate Momentus hard drives are a good fit in a variety of applications requiring robust performance. Key Features and Benefits
* Broad capacity range—30 GB to 160 GB * Low power consumption * Full disk encryption on FDE drive * Perpendicular recording technology * 5-year warranty
Momentus 5400 PSD Laptop Hybrid Drives
The Seagate® Momentus® 5400 PSD Hybrid Drive combines a hard drive and flash memory into a single device. Duplicating the most commonly used hard drive data onto the non-volatile cache for instant access provides faster boot-up and performance.
The Seagate® Momentus® 5400 PSD Hybrid Drive combines a hard drive and flash memory into a single device. Duplicating the most commonly used hard drive data onto the non-volatile cache for instant access provides faster boot-up and performance.
Notebook Computers Go Green - Seagate Hybrid Hard Drive Ushers in New Era of Power-Thrifty, Higher Performance Mobile Computing:
http://www.seagate.com/ww/v/index.jsp?locale=en-US&name=null&vgnextoid=f9be1194e3085110VgnVCM100000f5ee0a0aRCRD
Seagate has been at the forefront of introducing energy-saving features on its hard drives, and the new Momentus 5400 PSD hard drive ends the perennial trade-off for notebook PC makers. Laptop users want faster systems, but boosting laptop PC performance with higher speed components has traditionally meant higher power consumption and shorter battery life, raising the question: How do you reduce power consumption while delivering faster access to notebook data?
Combine power-efficient, quick-response flash memory with a fast hard disc drive.
The new Momentus 5400 PSD (Power Savings Drive) hard drive uses non-volatile cache, or flash memory, to cost-effectively deliver the benefits of solid state disc drives. The Momentus hard drive places commonly used hard drive data onto a large 256MB flash memory to deliver these capabilities:
Faster boot-up - Once a notebook is turned on, a traditional hard drive's platters must spin up before boot-up can begin. Hybrid hard drives load boot-up files on the flash memory to minimize this delay. Once the drive spins up, computer files are pulled simultaneously from the spinning media and the flash.
Lower power consumption - Seagate's Momentus 5400 PSD hard drives reduce hard disc drive power draw by up to 50 percent and extends battery life - especially important in mobile applications - by reducing platter spin time. In hybrid mode, the hard drive's spindle motors spin down, dramatically reducing the drive’s power requirements.
Greater reliability - Reducing platter spin time extends drive life by minimizing wear and tear. In hybrid mode, the drive locks its read-write heads in place, enabling the drive to withstand 900 Gs of shock, the rough equivalent of dropping a laptop from a height of six feet to a hard surface.
Higher performance - Hybrid hard drives also quicken access to laptop data. Windows Vista’s ReadyDrive technology uses Vista Superfetch to analyze computer usage patterns - such as how frequently a worker accesses certain files - and place commonly accessed user data in the flash memory to shorten system response time.
"We're thrilled Seagate is bringing to market hybrid hard drives that take full advantage of Windows Vista," said Dennis Moulton, product manager of Windows Client marketing at Microsoft. "It is this type of innovation in the ecosystem that helps move the bar, and we're excited about the productivity gains this helps bring to our customers in combination with Windows Vista."
All versions of Windows Vista deliver native support for hybrid drives, so system builders and end users alike can take advantage of hybrid hard drive technology today. Hybrid technology also delivers benefits for desktop, enterprise and other hard drives. Look for hybrid technology on other Seagate drive platforms in the future.
Videocast: Seagate Delivers Hybrid Hard Drive To view the videocast on the subject of Seagate’s new hybrid hard drives, please visit http://www.podtech.net/home/3805/seagate-announces-hybrid-drive-for-laptops.
About Seagate Seagate is the worldwide leader in the design, manufacture and marketing of hard disc drives, providing products for a wide-range of applications, including Enterprise, Desktop, Mobile Computing, Consumer Electronics and Branded Solutions. Seagate's business model leverages technology leadership and world-class manufacturing to deliver industry-leading innovation and quality to its global customers, and to be the low cost producer in all markets in which it participates. The company is committed to providing award-winning products, customer support and reliability to meet the world’s growing demand for information storage. Seagate can be found around the globe and at www.seagate.com.
Seagate, Seagate Technology and the Wave logo are registered trademarks of Seagate Technology LLC. Momentus is a trademark or registered trademark of Seagate Technology LLC. All other trademarks or registered trademarks are the property of their respective owners. One gigabyte, or GB, equals one billion bytes when referring to hard drive capacity. Accessible capacity may vary depending on operating environment and formatting.
External Disk Drives
Additional disks may be added using the external USB 2.0 ports.
Flash
A fair amount (512 MB) of NAND Flash (solid state non-volatile) memory will be provided on the XS server to allow the operating system and minimal services to continue operation even though the primary disk drive has failed.
A smaller amount (512KB) of NOR Flash will be provided for storage of configuration information and boot firmware.
On OTS systems, we are considering using adding USB keys or SD cards to allow similar functionality.
Power
The power specifications of the School server are important. Many schools do not have adequate, or regular, power. While the power consumption should be minimized (30W is a good target), consideration should be given to an integral (or optional modular) uninterruptible power supply (UPS). This is nothing more than a larger version of the laptop power supply!
In some test schools with minimal power, we are already deploying multiple (gang) battery chargers with integral UPS.
Possible methods of obtaining power are summarized in Battery_and_power.
Possible vendor for a Fanless redundant powersupply linked to an external daisychain expandable battery backup.
http://www.torchcomputers.co.uk/index.php?cPath=75
Environmental
Temperature
The school server should meet the same environmental specifications for temperature as the laptop. This is 50 C ambient.
Water, Dust, and Salt Fog
The server should be resistant to water spray from all directions, but does not have to survive immersion. It should be capable of long-term operation in a constantly humid (100%) environment, with salt fog and dust.
While the server will contain fans, they will externally accessible for easy replacement and under software control to conserve power.
Connectors and buttons should be resistant to water and dust intrusion. Buttons should be sealed against water, and connectors located and cables dressed to prevent water intrusion.
Mounting
While the school server should be designed to sit on a flat surface, it should probably also be mountable (hangable) from a wall or post.
This shouldn't cause a problem unless the server includes batteries for a optional/modular UPS...
Drop and Shake
The school server should meet higher drop and shake specifications than standard consumer desktop PCs, to account for rough transport in the delivery.
XSX Specifications
Right now, we using this term to refer to any hardware platform meeting the following criteria:
- 1GHz+ x86 processor
- 1 GB main memory
- four to six USB interfaces, with power for three Marvell Wifi nodes and an external disk drive.
- one 300GB+ 3.5in SATA drive (500 GB makes more sense right now)
- power and space for a second disk drive
- two 100baseT network interfaces (one will do in some cases)
- minimal fans
There are many hardware platforms meeting these specifications. We are working on a recommendation for a low power version.
